Side air bag device

ABSTRACT

The invention relates to a side air bag device embedded in a seat side which splits open a stitching part 26 of a seat covering material 20 by means of deployment pressure of an air bag 14 and deploys the air bag 14. In this device, a band 28 for concentrating deployment pressure of the air bag 14 on deployment of the air bag 14 is disposed, and a start to the stitching part 26 splitting open is made by means of this band 28. As a result, the stitching part 26 can be split open rapidly. Also, in the device, a seat pad 72 was interposed between an air bag case 16 and the seat covering material 20. As a result, the softness and feeling of the seat feel is not lost.

TECHNOLOGICAL FIELD

This invention relates to a side air bag device for protecting anoccupant from the side in the case of a collision accident of a vehicle.

BACKGROUND ART

An air bag device is a device for restraining an occupant by inflationof an air bag in the case of a vehicle collision, and generally is madeup of an inflator, which is a gas generator, an air bag capable ofinflating by gas from the inflator, and an air bag case housing the airbag and the inflator.

Air bag devices are not limited to those which restrain the occupantfrom the front, and recently, as disclosed in JP-A-06064491, ones whichrestrain from the side have been being developed. With these side airbag devices, for example, an air bag case housing the air bag and theinflator is embedded in a compartment wall side of a seat such as in thedoor side of a seat backrest, a seat covering material covering thesurface of the seat has in the vicinity of an opening of the air bagcase a stitching part where a covering material covering said openingand another covering material are stitched together, this stitching partis split open by a predetermined deployment pressure of the air bag, andthe air bag deploys through this split-open gap.

In the above-mentioned splitting-open of the stitching part, dependingmainly on differences in the elongation of the covering materials andthe elongation of the stitching thread, there is a type of thissplitting wherein the stitching part splits open as a result ofsewing-machine perforations of the cover material breaking and a typewherein the stitching part splits open as a result of the stitchingthread breaking.

The former type is widely used for example with composite seat coveringmaterials made of a vinyl chloride leather and a lining material, andthe latter type is widely used for example with composite seat coveringmaterials made by lining a fabric material (raised material, moquette)with a polyurethane foam seat material.

However, there is the limitation that in the case of the former type ofsplitting wherein sewing-machine perforations of the cover material areto be broken the strength of the stitching thread must be stronger thanthe strength of the covering material between sewing-machineperforations and in the case of the latter type of splitting wherein thestitching thread is to be broken reversely the seat covering materialmust be stronger, and both cases require a high-level balance in qualityand technology aspects.

It is therefore an object of a first invention of the invention toprovide a side air bag device, by discovering a new construction makinga start to splitting-open of a stitching part, with which easily it ispossible to achieve causing a stitching part to split-open rapidly, astrength balance between a seat covering material and a stitching threadcan be achieved simply and it is possible to increase productivitygreatly.

On the other hand, the conventional side air bag device described abovehas the shortcoming that because the air bag case is installedimmediately behind the seat covering material there is a hardness in thefeel from the seat surface.

It is therefore an object of a second invention of the invention toprovide a side air bag device with which by disposing a seat pad betweenthe air bag case and the seat covering material and using a constructionsuch that this pad can be split open it is possible to provide comfortwith excellent feel from the seat surface and with no feeling ofincongruity in the seat.

DISCLOSURE OF THE INVENTION

A side air bag device of the first invention of the invention is onewherein, in a side air bag device which is an air bag device embedded ina compartment wall side of a seat of a vehicle wherein a seat coveringmaterial has in the vicinity of an air bag case opening a stitching partwhere a covering material covering the opening and another coveringmaterial are stitched together and this stitching part is to be splitopen by means of a predetermined deployment pressure of an air bag, aband for suppressing elongation of the other covering material ondeployment of the air bag is provided extending between the othercovering material at the stitching part and a fixed member such as aseat frame, one end of the band is fixed to the fixed member and theother end of the band is co-stitched to the other covering material bymeans of stitching thread of the stitching part.

In this side air bag device, on deployment of the air bag the coveringmaterial covering the air bag case opening and the other coveringmaterial are first pushed by the internal pressure of the air bag, butbecause at this time elongation of the other covering material islimited by the band the force of the pushing of the air bag concentrateson the stitching of the band and as a result the stitching part of theseat covering material can be easily split open from this stitching partof the band. As a result of making a start to splitting-open of thestitching part by means of the band in this way this splitting-open canbe effected rapidly, and, a strength balance between the seat coveringmaterial and the stitching thread can be achieved easily and it ispossible to greatly raise productivity.

When giving examples of splitting-open forms of this stitching part ofthe seat covering material, depending mainly on differences in theelongation of the covering materials and the elongation of the stitchingthread, there are the following four:

1! The stitching part of the seat covering material is split open by thestitching thread starting to break from where the band is co-stitched.

2! The stitching part of the seat covering material is split open bysewing-machine perforations starting to break from where the band isco-stitched.

3! The stitching part of the seat covering material is split open by thestitching thread breaking and a small split being formed where the bandis co-stitched and this split then being enlarged by breaking ofsewing-machine perforations.

4! The stitching part of the seat covering material is split open bysewing-machine perforations breaking and a small split being formedwhere the band is co-stitched and this split then being enlarged bybreaking of the stitching thread.

Thus, the band initiates breaking of the stitching thread orsewing-machine perforations and the stitching part can be made to splitopen rapidly.

In a side air bag device according to this first invention, preferablythe band is disposed inclined with respect to the stitching line of thestitching part so that the deployment pressure of the air bagconcentrates at and splitting-open of the stitching part proceedsrapidly from one side of the stitching of the band. In this case,because the deployment pressure of the air bag is made to concentrate atone side of the stitching of the band, splitting-open of the stitchingpart can be made more rapid and there are also merits such as that it ispossible to obtain a predetermined splitting-open starting point.

In a side air bag device according to this first invention it is alsopreferable from the point of further facilitating splitting-open of thestitching part that the end of the band on the seat covering materialside be so stitched that it moves in a direction peeling from thestitching part when pulled by the other covering material on deploymentof the air bag.

Also, in a side air bag device according to this first invention, theband may be disposed passing between the air bag case and the case sidecovering material.

A side air bag device of the second invention of the invention is onewherein, in a side air bag device which is an air bag device embedded ina compartment wall side of a seat of a vehicle wherein seat coveringmaterials are stitched so as to be joined together in the vicinity of anair bag case opening and this stitching part is to be split open bymeans of a predetermined deployment pressure of an air bag, a seat padof a predetermined thickness is interposed between the air bag case andthe covering materials and a slit part for allowing the air bag to passthrough the pad on deployment is formed in the pad on the inner side ofthe stitching part. By the air bag case, which conventionally has beenadjacent to the seat covering material, being covered with the pad inthis way, it is possible to install the side air bag device withoutlosing the softness or the feeling of the feel of the seat.

In a side air bag device according to this second invention, in the partof the pad on the inner side of the seat covering material stitchingpart, instead of forming a slit part for allowing the air bag to passthrough on deployment, a weak part to be split open by deploymentpressure of the air bag and allow the air bag to pass through mayformed. This weak part can be formed by making the pad thinner than thesurrounding. Also, this weak part may be one formed by providing holesor slits intermittently in the form of a tear line.

In a side air bag device according to this second invention, the shapeof the slit part or the weak part can be a straight line shape or abracket-like shape, and ends of the slit part or the weak part may beterminated into a circular shape, a T-shape, an L-shape or a U-shape.Also, the thickness of parts of the pad adjacent to the slit part or theweak part can be made thin in the vicinity of the center of the slitpart or the weak part and thick at its ends. By these end treatments, ondeployment of the air bag, in the case of the slit part it is possibleto prevent its ends from tearing and in the case of the weak part it ispossible to make the pad split open with a predetermined shape.

Also, in a side air bag device according to the second invention of theinvention, a pad in a side of the seat in which the slit part or theweak part is formed can be made harder than a pad of another part of theseat and formed integrally with the pad of another part of the seat. Asa result, because maintenance of the shape of the slit part or weak partbecomes easy, it is possible to make the positional relationship of theslit part or the weak part with respect to the air bag fixed andconcentrate the deployment pressure of the air bag on the slit part orthe weak part and it is possible to make the position of the part of thepad which splits open fixed. Also, because it is possible to make thepad highly elastic with respect to the deployment pressure of theinflating air bag it is possible to increase the strength of a hingepart of the pad opened outward by the splitting-open of the pad. It isalso effective in increasing the firmness with which the occupant isheld in the seat.

In a side air bag device according to the second invention of theinvention it is also possible to form a skin layer of thickness 30 to200 μm at the surface of the pad in the vicinity of the slit part or theweak part, and by this means the surface of the pad in the vicinity ofthe slit part or weak part can be protected.

The construction of this second invention may also be applied to a sideair bag device according to the above-mentioned first invention. Thatis, in a side air bag device embedded in a compartment wall side of aseat of a vehicle which by means of a predetermined deployment pressureof an air bag splits open a stitching part in a seat covering materialwhere a covering material covering an opening in an air bag case andanother covering material are stitched together in the vicinity of theopening in the air bag case, a seat pad of a predetermined thickness maybe interposed between the air bag case and the seat covering materialand a slit part or a weak part for allowing the air bag to pass throughon deployment may be formed in the pad on the inner side of thestitching part and a band for suppressing elongation of the othercovering material on deployment of the air bag may be provided extendingbetween the other covering material at the stitching part and a fixedmember such as a seat frame, one end of the band may be fixed to thefixed member and the other end of the band may be co-stitched to theother covering material by means of stitching thread of the stitchingpart. With this construction, the softness and feeling of the seat arenot lost and it is possible to make the stitching part split openrapidly on deployment of the air bag.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of part of a compartment interior showing aside air bag device of an embodiment of a first invention of theinvention after the device has operated,

FIG. 2 is a perspective view of a seat fitted with this air bag device,

FIG. 3 is a horizontal sectional view of this air bag device,

FIG. 4 is outline horizontal sectional views illustrating the operationof this air bag device, (a) showing the device before operation and (b)showing an initial stage and (c) a final stage in its operation,

FIG. 5(a) is a perspective view of the device in the state shown in thepreceding figure (b), and FIG. 5(b) is a perspective view of the devicein the state shown in the preceding figure (c).

FIG. 6 is a perspective view showing an example of fixing of a band inthis air bag device to a fixed member,

FIG. 7 is views showing another example of fixing of the band to thefixed member, (a) being a perspective view and (b) a sectional view.

FIG. 8 is a sectional view showing another example of stitching of theband to the seat covering material.

FIG. 9 is a perspective view of a seat fitted with a side air bag deviceof another embodiment of the first invention of the invention,

FIG. 10 is a front view showing an example of stitching of a band inthis air bag device to a seat covering material,

FIG. 11 is perspective views illustrating the operation of this air bagdevice, (a) showing an initial stage and (b) a final stage in itsoperation.

FIG. 12 is a front view showing another example of stitching of a bandin this air bag device,

FIG. 13 is a front view showing a further example of stitching of aband,

FIG. 14 is a front view showing a further example of stitching of aband,

FIG. 15 is a front view showing a further example of stitching of aband.

FIG. 16 is horizontal sectional view showing a side air bag device ofanother embodiment of the first invention of the invention,

FIG. 17 is outline horizontal sectional views illustrating the operationof this air bag device, (a) showing the device before operation and (b)showing an initial stage and (c) a final stage in its operation.

FIG. 18 is a horizontal sectional view showing a side air bag device ofan embodiment of a second invention of the invention,

FIG. 19 is a perspective view of a backrest of a seat fitted with thisair bag device, with a seat covering material removed,

FIG. 20 is a horizontal sectional view showing another example of a slitpart of this air bag device,

FIG. 21 is a perspective view of a backrest of a seat fitted with thedevice shown in FIG. 20, with a seat covering material removed.

FIG. 22 is a horizontal sectional view showing a side air bag device ofanother embodiment of the second invention of the invention,

FIG. 23 is a perspective view of a backrest of a seat with a seatcovering material removed showing another example of a weak part of thisair bag device.

FIG. 24 is a horizontal sectional view of a side air bag device ofanother embodiment of the second invention of the invention,

FIG. 25 is a perspective view of a backrest of a seat fitted with thisair bag device, with a seat covering material removed.

FIG. 26 is a perspective view of a backrest of a seat with a seatcovering material removed showing an example of the shape of a slit partor a weak part,

FIG. 27 is a perspective view of a backrest of a seat with a seatcovering material removed showing another example of the shape of a slitpart or a weak part.

FIG. 28 is sketches of examples of modifications to the slit part or theweak part shown in FIG. 26, in (a) through (d) the shape of the ends ofthe slit part or the weak part and in (e) the pad thickness around theslit part or the weak part being modified.

FIG. 29 is sketches of modifications to the slit part or the weak partshown in FIG. 27, in (a) through (d) the shape of the ends of the slitpart or the weak part and in (e) the pad thickness around the slit partor the weak part being modified.

FIG. 30 is a perspective view of a backrest of a seat with a seatcovering material removed showing an example wherein a side pad of theseat is made of a foam of a different hardness,

FIG. 31 is an outline sectional view showing a state of the side pad ofthe seat of the preceding figure on splitting-open.

FIG. 32 is a sectional view showing a skin layer formed at the padsurface in the vicinity of a slit part or a weak part,

FIG. 33 is a sectional view of a mold illustrating an example of moldingof a seat pad.

PREFERRED EMBODIMENTS OF THE INVENTION

FIGS. 1 through 3 show a side air bag device of a first embodiment ofthe first invention of the invention.

This side air bag device 10 has an inflator 12, an air bag 14 and an airbag case 16 and is embedded in the compartment wall (door) 20 side of abackrest 18a of a seat 18 of a vehicle, as shown in FIGS. 1 through 3,and in an emergency deploys the air bag 14 toward the front of thevehicle between the occupant and the compartment wall 20, as shown inFIGS. 1 and 3.

A seat covering material 20 covering the surface of the seat 18 has astitching part 26 where two covering materials 22, 24 are stitchedtogether at the side of the front of the air bag case 16. That is, asshown in FIG. 3, at the side of an opening 16a in the air bag case 16, acase side covering material 22 covering this case opening 16a and anoccupant side covering material 24 extending from this toward the side Gon which the occupant sits are projected together and stitched, and thisstitching part 26 is disposed inside the seat 18 and extends in aroughly vertically direction along the backrest 18a as shown in FIG. 2.As a result of stitching thread 27 of this stitching part 26 beingbroken by a predetermined deployment pressure of the air bag 14, thestitching part 26 splits open and the air bag 14 expands through thisgap.

In this side air bag device 10, a band 28 for suppressing elongation ofthe occupant side covering material 24 on deployment of the air bag 14is provided extending between the occupant side covering material 24 atthe stitching part 26 and a fixed member 30 such as a seat frame (or theair bag case 16), the fixed member side end 28b of this band 28 is fixedto this fixed member 30, and the seat covering material side end 28a isco-stitched to the occupant side covering material 24 with the stitchingthread 27 of the stitching part 26.

The fixed member side end 28b of this band 28 is fixed to the fixedmember 30 by way of a bracket 32 and a bolt nut 34, as shown in FIG. 3and FIG. 6. For this fixing, as shown in FIG. 7, alternatively a hook 37or a karabiner-like ring hook (not shown) forcibly fitted onto a roundbar 36 of the seat frame or the like may be attached to the fixed memberside end 28b of the band 28, and it thereby engaged with the fixedmember 30.

As shown in FIG. 3, the seat covering material side end 28a of the band28 is stitched reversely-facing so that it moves in a peeling directionwhen pulled by the occupant side covering material 24 on deployment ofthe air bag 14. This seat covering material side end 28a mayalternatively be stitched so as to move in a shearing direction whenpulled by the occupant side covering material 24, as shown in FIG. 8.However, from the point that it makes it possible to break the stitchingthread 27 more easily, stitching the seat covering material side end 28aso that it moves in a peeling direction, as described above, ispreferable.

This band 28 is preferably made of a cloth made of nylon or polyester orthe like having low elongation, and its width should be about 20 to 30mm. The width of the band 28 is preferably narrow like this compared tothe width of the air bag 14 (about 300 mm) because it then concentratesstress applied by the deployment pressure of the air bag 14. However,depending on the position in which the air bag case 16 is embedded, whenthe width of the band 28 is too narrow compared to the width of the airbag 14, it sometimes happens that the air bag 14 is bent by the band 28during its inflation (i.e., the air bag 14 expands around the sides ofthe band 28) and it is difficult to obtain rapid inflation. For thisreason, in such cases, the width of the band 28 is preferably about 150to 400 mm so that the band 28 guides the air bag 14 until the whole ofthe stitching part 26 has broken. This band 28 can be made of resin ormetal instead of cloth, but in that case a hardness remains in the feelof the seat.

In this side air bag device 10, when the air bag 14 starts to inflatefrom the state shown in FIG. 4(a), as shown in FIG. 4(b) and FIG. 5(a),deployment pressure of the air bag 14 first pushes the case sidecovering material 22 and the occupant side covering material 24 outward.Consequently, the occupant side covering material 24 tends to elongatetogether with the case side covering material 22, but because elongationof the occupant side covering material 24 is regulated by the band 28,the force of the pushing of the air bag 14 concentrates on the stitchingpart 26 at the band 28. As a result, as shown in FIG. 4(c) and FIG.5(b), the stitching thread 27 starts to break from this part and thestitching part 26 of the two covering materials 22, 24 splits open.Because the pushing force of the air bag 14 is concentrated on thestitching part 26 at the band 28 like this, breaking of the stitchingthread 27 holding together the covering materials 22, 24 is easy andconsequently the stitching part 26 can be split open rapidly.

In the embodiment described above, splitting-open of the stitching part26 is effected by breaking of the stitching thread 27; however,according to the strength balance between the covering materials 22, 24and the stitching thread 27, splitting open of the stitching part 26 canalso be made to take any of the following other forms.

That is, this splitting-open can be made to take any form such as onewherein sewing-machine perforations start to break from where the band28 is stitched and the sewing-machine perforations of the stitching part26 of the covering materials 22, 24 are entirely broken,

one wherein the stitching thread 27 where the band 28 is stitched breaksand the band 28 peels away and a small split is formed in the stitchingpart 26 and then this split is enlarged by breaking of sewing-machineperforations of the covering materials 22, 24 by the pushing of the airbag 14,

or one wherein sewing-machine perforations where the band 28 is stitchedbreak and the band 28 peels and consequently a small split is formed inthe stitching part 26 and then this split is enlarged by breaking of thestitching thread 27 by the pushing of the air bag 14. This is also thesame in the cases of all the air bag devices discussed hereinafter.

FIG. 9 shows a side air bag device 50 of another embodiment of the firstinvention.

In this side air bag device 50, the orientation of the band 28 withrespect to the stitching part 26 is different from in the side air bagdevice 10 of the embodiment described above. That is, this embodimenthas the characteristic that, as shown in FIG. 10, the band 28 isdisposed so that the long axis line X, or length direction, of the band28 is not perpendicular but rather is inclined with respect to thestitching line Y of the stitching part 26, so that deployment pressureof the air bag 14 concentrates at one side 28c of the stitching of theband 28 and splitting-open of the stitching part 26 occurs rapidlystarting from this part.

By this means, in this side air bag device 50, as shown in FIG. 11, whenon deployment of the air bag 14 the case side and occupant side coveringmaterials 22, 24 are pushed by the deployment pressure of the air bag14, this pushing force concentrates on the one side 28c of the stitchingof the band 28. Consequently, the stitching thread 27 starts to breakfrom this part and the stitching part 26 of the covering materials 22,24 splits open rapidly. Because by the band 28 being disposed inclinedwith respect to the stitching line Y of the stitching part 26 in thisway it is possible to make the deployment pressure of the air bag 14concentrate on a single point on the stitching part 26 at the band 28,the stitching thread 27 of the stitching part 26 can be made to breakrelatively easily and consequently more rapid splitting-open of thestitching part 26 becomes possible. Also, because the stitching thread27 starts to break from the above-mentioned single point, there aremerits such as that a predetermined starting point of splitting can beobtained.

When the band 28 is disposed inclined with respect to the stitching lineY of the stitching part 26 in this way, it is made basic to dispose asingle band 28 pointing diagonally downward with respect to thestitching line Y of the stitching part 26 at an acute angle ofelevation, as shown in FIG. 10, but instead of this, one of two bands28, 28 may be disposed pointing diagonally downward with respect to thestitching line Y of the stitching part 26 and the other may be disposedpointing diagonally upward with respect to the stitching line Y, asshown in FIG. 12. Also, as shown in FIG. 13 and FIG. 14, the seatcovering material side end 28a of the band 28 may be extended and bentand stitched along the stitching line Y. Or, as shown in FIG. 15, asingle band 28 may be bent in a V-shape and the bent portion stitched tothe stitching part 26 as a seat covering material side end 28a and twofixed member side ends 28b, 28b respectively extending upward anddownward from there may be brought together and fixed to the fixedmember 30 with a single bolt 32.

Also, the band 28, besides being one stitched while oriented at anincline with respect to the stitching line Y of the stitching part 26 asdescribed above, may alternatively be made one stitched whileperpendicular with respect to the stitching line Y of the stitching part26 and then oriented at an incline by for example having its fixedmember side end 28b fixed diagonally above or diagonally below the seatcovering material side end 28a.

FIG. 16 shows a side air bag device 60 of another embodiment of thefirst invention of the invention.

This side air bag device 60 differs from the side air bag device 10described above in the point that the band 28 extending between theoccupant side covering material 24 at the stitching part 26 and thefixed member 30 is disposed passing between the air bag case 16 and thecase side covering material 22. That is, in this embodiment, the band 28is disposed extending rearward passing between the opening 16a of theair bag case 16 and the case side covering material 22 from the seatcovering material side end 28a stitched to the stitching part 26 and thefixed member side end 28b is fixed to the fixed member 30 behind the airbag case 16.

Also when it is disposed like this, as shown in FIG. 17, the pushingforce of the air bag 14 is concentrated on the stitching part 26 at theband 28 and the stitching part 26 can be rapidly split open. Also, inthe case of this side air bag device 60, since it is possible to fix thefixed member side end 28b to the fixed member 30 from the back of theseat 18 after the seat covering material side end 28a is stitched to thestitching part 26, its manufacture is easy.

FIG. 18 shows a side air bag device of an embodiment of the secondinvention of the invention.

In the side air bag device 70 of this embodiment also, as in the sideair bag device 10 described above, an air bag case 16 housing aninflator 12 and an air bag 14 is embedded in the compartment wall 20side of a backrest 18a of a seat 18, a case side covering material 22and an occupant side covering material 24 are stitched togetherdiagonally in front of the opening 16a in the air bag case 16, and bythis stitching part 26 being split open by a predetermined deploymentpressure of the air bag 14 the air bag 14 is able to expand between theoccupant and the compartment wall 20 in an emergency.

In the side air bag device 70 of this embodiment, a urethane foam pad 72of a predetermined thickness is interposed between the air bag case 16and the seat covering material 20. That is, urethane foam pads 72, 73are disposed not only in the side G of the seat 18 on which the occupantsits but also in the seat side in which the side air bag device 70 isinstalled. A slit part 74 which allows the air bag 14 to pass throughthe pad on deployment of the air bag 14 is formed in the part of thispad 72 that is on the inner side of the stitching part 26 of thecovering materials 22, 24.

As shown in FIG. 19, this slit part 74 is formed extending in an up-downdirection along the side of the seat backrest 18a alongside thestitching part 26. As this slit part 74, any slit part from the onehaving no gap shown in FIG. 18 and FIG. 19 to the one having a gap ofabout 5 mm shown in FIG. 20 and FIG. 21 is suitable, and as the lengthof the slit, so that the air bag 14 can pass through, about 300 to 500mm is suitable.

In the side air bag device 70 of this embodiment, because the urethanefoam pad 72 is interposed between the air bag case 16 and the coveringmaterials 22, 24 covering it, the feel of the seat from the seat surfaceis superior. Also, because the slit part 74 is provided in this pad 72,there is the effect that the air bag 14 can pass through on deploymentand inflation of the air bag 14 in a predetermined position becomespossible. Even when a slit part 74 is provided in the urethane foam pad72 like this, because of the presence of the seat covering material 20on the seat surface, a seat with its feeling maintained is possible.

FIG. 22 shows a side air bag device 80 of another embodiment of thesecond invention. This side air bag device 80 differs from the side airbag device 70 of the embodiment described above in the point that,instead of a slit part 74, a weak part 82 for being split open bydeployment pressure of the air bag 14 and allowing the air bag 14 topass through is formed in the pad 72 disposed between the air bag case16 and the seat covering material 20. That is, in this example, a weakpart 82 made by making the pad thinner than the surrounding is formed inthe part of the pad 72 on the inner side of the stitching part 26extending in an up-down direction along the side of the seat backrest18a alongside the stitching part 26, and on deployment of the air bag 14the weak part 82 is split open by the deployment pressure of the air bag14 and the air bag 14 expands to outside the seat through this gap. Whenthe weak part 82 is formed by locally making the pad thinner like this,it is preferably formed as if by scooping out the inner wall side of thepad 72, as shown in FIG. 22.

FIG. 23 shows another version of the weak part 82, and in this examplethe weak part 82 is formed by providing holes or slits in the pad 72intermittently in the form of a tear line.

In the cases shown in FIG. 22 and FIG. 23 wherein a weak part 82 isformed in the pad 72, because compared to when a slit part 74 is formedthe integrity of the urethane foam pad 72 is higher, it is possible tofurther preserve the feeling of the seat 18. To make the weak part 82split open easily, a small slit, which will be further discussed later,may be provided in the weak part 82.

FIG. 24 and FIG. 25 show a side air bag device 90 of another embodimentof the second invention. This side air bag device 90 is one wherein theconstruction of the first invention of the invention is added to theside air bag device 80 of the embodiment described above.

That is, in this side air bag device 90, as well as a urethane foam pad72 being interposed between the air bag case 16 and the coveringmaterials 22, 24, a weak part 82 for splitting open on deployment of theair bag 14 and allowing the air bag 14 to pass through is formed in thepad 72 on the inner side of the seat covering material stitching part26. This weak part 82 has in the middle thereof a small slit part 82a,and a band 28 for suppressing elongation of the occupant side coveringmaterial 24 during inflation of the air bag 14 is disposed passingthrough this small slit part 82a from inside to outside. The band 28,like that described in detail in embodiments of the first invention, isdisposed extending between an occupant side covering material 24 at thestitching part 26 and a fixed member 30 such as a seat frame, and oneend 28b thereof is fixed to the fixed member 30 and the other end 28a isco-stitched to the occupant side covering material 24 with stitchingthread 27 of the stitching part 26.

With this side air bag device 90, while maintaining the softness of thefeel of the seat, it is possible to make the seat covering materialstitching part 26 split open rapidly on deployment of the air bag 14.Instead of the weak part 82, a slit part 74 of the kind described abovemay be provided and the band 28 made to pass through this slit part 74.

In all the embodiments of the second invention described above, theshape of the slit part 74 or the weak part 82 can be made a straightline shape of the kind shown in FIG. 26 or a bracket-like shape of thekind shown in FIG. 27. It is also possible to form the upper and lowerends of the slit part 74 or the weak part 82 into a circle shape asshown in FIG. 28(a) and FIG. 29(a), into a T-shape as shown in FIG.28(b) and FIG. 29(b), into an L-shape as shown in FIG. 28(c) and FIG.29(c) or into a U-shape as shown in FIG. 28(d) and FIG. 29(d). Also, asshown in FIG. 28(e) and FIG. 29(e), it is possible to make the thicknessof parts of the pad 72 adjacent to the slit part 74 or the weak part 82thin in a central vicinity C of the slit part 74 or the weak part 82 andthicker with progress toward the end parts T.

By these terminating treatments, in the case of a slit part 74 it ispossible to prevent the upper and lower ends thereof from tearing ondeployment of the air bag 14 and in the case of a weak part 82 it ispossible to make the pad 72 split open with a predetermined shape (thatis, it is possible to make splitting-open of the pad end at thosepositions).

Also, in all the embodiments of the second invention of the invention,as shown as diagonal line areas in FIG. 30, it is possible to form aseat side pad 72 in which a slit part 74 or a weak part 82 is formed,and, depending on the case, the side of the opposite side of the seat,using a urethane foam harder than that of the central pad 73 andintegral with the pad 73. In this case, the side pad 72 is formedintegrally using for example low molecular weight or highly crosslinkedurethane foam of a different hardness.

Because this makes shape maintenance of the slit part 74 or the weakpart 82 easy, it is possible to fix the positional relationship of theslit part 74 or the weak part 82 with respect to the air bag 14 andconcentrate the deployment pressure of the air bag 14 on the slit part74 or the weak part 82, and the position at which the pad 72 splits opencan also be fixed. That is, when the pad 72 is of low hardness,sometimes for example under the body weight of an occupant partially itis not possible to maintain the predetermined shape of the pad and itscross-sectional shape and contours deform, and consequently the obtainedeffect of stress concentrating at the slit part 74 or the weak part 82might decrease; however, by making the side pad 72 hard as describedabove it is possible to eliminate this problem. Also, because it ispossible to make the pad 72 highly elastic with respect to thedeployment pressure of the air bag 14, the strength of a hinge part 72aof the pad 72 opening outward after splitting as shown in FIG. 31 can beincreased. Furthermore, making the seat side pads harder is alsoeffective in increasing the firmness with which the occupant is held inthe seat.

Also, in all the embodiments of the second invention, by adjusting thesurface temperature of molds and the foam pressure during urethane foammolding, a solid skin layer 92 of thickness about 30 to 200 μm may beformed at the surface of the pad 72 in the vicinity of the slit part 74or the weak part 82, as shown in FIG. 32.

For example, as shown in FIG. 33, when carrying out urethane foammolding using an upper mold 95 and a lower mold 96, the above-mentionedskin layer 92 can be formed by making the temperature of a mold formingpiece 97 for forming a slit part 74 or a weak part 82 lower than thesurface temperature of the rest of the upper and lower molds 95, 96. Inthis case, as shown in FIG. 32, a skin layer 92 is formed at the surfaceof the urethane of the slit part 74 or the weak part 82 for the air bag14 to pass through on deployment, and from the surface by way of amicrocell layer 93, which is a fine foam layer, to a cell layer 94 whichis an ordinary foam layer, the foam diameter successively increases. Byforming a skin layer 92 like this it is possible to protect the surfaceof the pad 72 with which the air bag 14 makes contact on deployment ofthe air bag 14 and splitting-open of the pad 72 with a neat splitsurface is possible.

The slit part 74 and the weak part 82 in all the embodiments of thesecond invention can also be formed by a cutting process using a cutterknife or a sander or the like. A cutting process can be carried outeasily by hand without special equipment being required and is suitablefor low-volume production, and molding is suitable for mass-production.

Industrial Applicability

In a side air bag device of this invention, because a band for startingsplitting-open of a stitching part is provided, the stitching part canbe split open rapidly and because a strength balance between the seatcovering material and the stitching thread can be achieved easily it ispossible to greatly increase productivity.

Also, in a side air bag device of the invention, because a seat pad isinterposed between the air bag case and the seat covering material, itis possible to install the side air bag device in a seat withoutimpairing the softness and feeling of the feel of the seat.

We claim:
 1. A side air bag device which is an air bag device embedded in a compartment wall side of a seat of a vehicle wherein a seat covering material has in the vicinity of an air bag case opening a stitching part where a case side covering material covering the opening and an occupant side covering material are stitched together by said stitching part and this stitching part is to be split open by means of a predetermined deployment pressure of an air bag,said side air bag device characterized in that a seat pad of a predetermined thickness is interposed between the air bag case and the seat covering material and a slit part or a weak part for allowing the air bag to pass through on deployment is formed in the pad on the inner side of the stitching part, and also a band for suppressing elongation of the occupant side covering material on deployment of the air bag is provided extending between the occupant side covering material at the stitching part and a fixed member such as a seat frame, one end of the band is fixed to the fixed member and the other end of the band is co-stitched to the occupant side covering material by means of stitching thread of the stitching part.
 2. A side air bag device according to claim 1, characterized in that the shape of the slit part or the weak part forms a straight line shape or a bracket-like shape.
 3. A side air bag device according to claim 2, characterized in that an end of the slit part or the weak part is terminated into a circular shape, a T-shape, an L-shape or a U-shape.
 4. A side air bag device according to claim 1, characterized in that the thickness of a part of the seat pad adjacent to the slit part or the weak part is made thin in the vicinity of the center of and thick at an end of the slit part or the weak part.
 5. A side air bag device according to claim 1, characterized in that a part of said seat pad in a side of the seat in which the slit part or the weak part is formed is made harder than a part of said seat pad of another part of the seat and is formed integrally with the part of said seat pad of the other part of the seat.
 6. A side air bag device according to claim 1, characterized in that a skin layer of thickness 30 to 200 μm is formed at the surface of the pad in the vicinity of the slit part or the weak part. 